Alarm system for a tissue processor

A shut-down and/or annunciator system for a vacuum vessel arranged to be filled with liquid by application of a vacuum thereto comprising:

• a vacuum sensitive switch that outputs a logic signal having a first state indicative of whether the vacuum in the vessel is sufficiently high to draw liquid into the vessel and a second state indicative of a vacuum diminished as a result of air being drawn into the vessel;
• a timer circuit for generating first and second gate signals, the first gate signal during the first few seconds of a filling period and the second gate signal just after the time when the vessel is normally filled;
• means for generating a short duration shut-down signal in response to the first gate signal and the output of the vacuum switch;
• means for generating a short duration shut-down signal in response to the second gate signal and the inverted output of the vacuum switch;
• and
• a mechanical latch responsive to said shut-down signals for outputting a continuous shut-down and/or alarm signal.

A shut-down and/or annunciator system for a vacuum vessel arranged to be filled with liquid by application of a vacuum thereto comprising:

• a vacuum sensitive switch that outputs a logic signal indicative of whether the vacuum in the vessel is above or below a preselected level;
• a timer comprising a motor driven potentiometer, a resistor divider and a plurality of op amps level detectors for generating first and second gate signals, the first gate signal during the first few seconds of a filling period and the second gate signal during the last few seconds of the filling period;
• means comprising a digital logic circuit for generating a short duration shut-down signal in response to the first gate signal and the output of the vacuum switch or the second gate signal and the output of the vacuum switch;
• and
• a mechanical latch comprising a latching relay switch and a transition switch on the coil circuit thereof, said latch responsive to said shut-down signal for outputting a continuous shut-down and/or alarm signal.